1. Field of the Invention
Embodiments of the invention described herein pertain to the field of computer systems. More particularly, but not by way of limitation, one or more embodiments of the invention enable systems and methods for wavelet-based standard 1080p-high definition and extra-high definition multi-dimensional and channel-based video encoding.
2. Description of Related Art
Video may be stored in digital form. In its uncompressed state, digital video exists as a series of images, or video frames. High definition digital video in its uncompressed state usually involves so much data that it must immediately be either consumed or compressed for transmission or storage, for later decompression and consumption. This problem is resolved with the help of a video encoder that compresses the video to a fraction of its original size. At playback time, with the help of a general or special purpose digital processing device, a corresponding video decoder decompresses and reconstructs the video for display. The success of this process depends on the amount and kind of data lost in the compression process; the size, resolution, and frame rate of the display; the available computer resources; and the efficiency of the decoder. The first and last of these issues depend on the video encoder and decoder, i.e., the video codec.
Over the years, the meaning of ‘high definition’ video, implying higher than ordinary resolution viewing, increased until its meaning was standardized. Standard high definition (HD) modes include 720p (1,280×720), 1080i (1,920×1,080 interlaced), 1080p (1,920×1,080). Extra HD modes have emerged, including 2K (2,048×1,536), 2160p (3,840×2,160), 4K (4,096×3,072), 2540p (4,520×2,540), and 4320p (7,680×4,320).
Video compression is useful to improve transmission speed, reduce storage size, reduce required bandwidth, and improve video quality. Video compression and decompression techniques affect digital video transmission. Some video compression techniques result in digital video files that are streamable (i.e., may be transmitted, decompressed, and displayed in real time). Video compression may employ lossless or lossy data compression techniques. Lossy data compression can affect video quality.
The primary issue in video encoding is achieving adequate video compression to satisfy transmission bandwidth and storage media limitations, without too severely compromising visual quality.
Existing video codecs must often trade off viewing quality to satisfy high definition standards, memory limitations and, especially, communication bandwidth limitations. The trade-space available to satisfy these requirements is limited for codecs based on the discrete cosine transform (DCT). Today's conventional method for encoding video uses the DCT to transform the video signal from the image domain to the frequency domain. Such frequency-domain video compression is used in such standards as MPEG-2, MPEG-4, Windows Media, and H.264 standard codecs. Because the DCT is suitable only for very small blocks of data, an HD video frame must be partitioned into thousands of distinct DCT blocks, a major processing challenge for the decoder, which must somehow make block boundaries invisible to the viewer. Moreover, such codecs also require motion prediction for further compression in the time domain, using motion vectors relative to key frames (e.g., ‘I-frames). Such a process makes random access to non-key frames a time-intensive process and makes it difficult to do video editing. Even primary colors are decorrelated to satisfy compression requirements. There are many implementations but only one DCT transform. The DCT has been fully exploited for video applications. As industry struggles with DCT-based codecs to satisfy even the rudimentary 1280×720p HD standard, with 4320p imminent, there is no clear path to achieving the compression and quality demanded by extra-high definition video.
Wavelet transforms have been applied to compression for still images (e.g., JPEG 2000), but video codecs using wavelets have been found to be too slow and too lacking in viewing quality to be practical even for many non-HD video applications. Wavelets have been used inefficiently in video codecs (slowing down the decoder) and/or ineffectively (taking only limited advantage of their potential and producing video of inferior quality). These kinds of implementation problems have discouraged any significant use of wavelets in practical applications and have prevented any use of wavelets in HD or 3-D video applications. Indeed, existing techniques do not provide compression required for today's standard HD video, nor do they address the loss of video quality typical of wavelet-based codecs.
There is a need for systems and methods for wavelet-based standard high definition and extra-high definition two and three-dimensional channel-based video encoding that overcomes these issues.